R4i-B9S is a compatible DS / DSi flashcart that is pre-flashed ntrboot, then you can
easily install boot9strap and Luma 3DS CFW on your 3DS or 2DS and it also supports
flashing B9S to NDS flashcart or reversely.

R4i-B9S flashcard FAQ

Q: Can B9S switch to NDS flashcart to play ds games?

A: Yes, you can use a B9S flasher to switch.

Q: Can Nintendo patch this?

A: Nope! Not without a new hardware revision.

Q: My flashcard is blocked by my firmware! Can I still use R4i-B9S card?

A: Yes! The flashcard blacklist is not enabled on the bootrom.

Q: Why can’t this work with other flashcard?

A: The installation requires you to flash NTRBoot to the flashcard’s nand. Not all flashcards have this!

Q: Can you make sure it works?

A: Yes, we are the manufacturer, and we know best what the flash card should be done.

Q: Can I unbrick from a brick?

A: Considering the card has access to the bootrom, most likely yes! This can potentially unbrick any brick (except MCU), unless you’ve taken a knife to the motherboard.

Q: Does this work on the New Nintendo 2DS XL?

A: Yes. Perfect support for 3DS(XL)/NEW 3DS(XL)/2DS/NEW 2DS(XL)

Q: Can I do this with a 8GB (or smaller) SD card?

A: Yes!

Q: Can I use a 128GB (or larger) SD card?

A: Yes, but some users have reported slowdowns when using such large sizes. Note that you cannot format the card with exFAT; you need to format it with FAT32.